Creating an environment variable

Hello, am new to react native and am attempting my first Eas build on vscode and i got this message ; Loaded “env” configuration for the “preview” profile: no environment variables specified. Learn more: Environment variables and secrets in EAS Build - Expo Documentation

In the link above attached to my message state that for creating an environment variable in SDK 48, its recommended to use direnv but the normal way I know is through dotenv. The question now is which one should I use because right now am confused